The present invention relates to archery bows for uses such as hunting or target shooting and more particularly to an improved archery bow having a tensioning device to vary the force required to bend the bow during the time when the bow is in use or being drawn.
Archery bows are normally constructed to provide an elongated curvilinear body having a midportion of increased cross section and tapering towards opposite ends to terminate in tip portions which are interconnected by the bowstring. The bow is usually made of a flexible material and the tapered configuration adds to the flexibility of the bow when the bowstring is tensioned by the placement and drawing of an arrow on the string.
For greater accuracy in aiming the arrow it would be desirable to lessen the tension required to hold the bowstring completely drawn for hunting or target shooting conditions. Thus, under those circumstances, lessening the drawn tension would help steady the archer's arm when the bow is aimed, notwithstanding the large forces necessary to obtain adequate arrow propelling speed. It is also desirable to apply the propelling force to the arrow in a smooth manner thus eliminating the application of impact forces which could upset the aim and direction of the arrow.
It is known to adjustably mount the bowstring so that its position can be varied at the tip ends of the bow to thereby increase or decrease the effective length of the bow adding more stiffness to the bow as the string is moved towards the center of the bow and increasing the flexibility of the bow as the string is moved further outwardly towards the tip ends. However, this arrangement is unsatisfactory in that it foreshortens the arrow draw, in that only a limited number of positions are available to vary the tension force required to bend the bow, and in that only static settings are attainable.
Similarly, a limitation in conventional bow design is that the energy which may be stored in the limbs is limited by the archer's muscular ability to sustain a bow at full draw.
Prior art bows also have constructions whereby the power of a bow may be dynamically adjusted by various means such as springs, cams, eccentrics and the like, and such bows are called "compound" bows. However, most of the latter devices are awkward and complicated, and the usefulness and accuracy of such bows has been handicapped to some extent by such limitations.